int a = 5;
private void button1_Click(object sender, EventArgs e)
{
timer1.Enabled = true;
timer1.Interval = 1000;
}
private void timer1_Tick(object sender, EventArgs e)
{
string temp;
temp = textBox1.Text + textBox1.Text;
label1.Text = temp.Substring(a,5);
a++;
if (a > textBox1.Text.Length)
a = 1;
}